Optics for high-power light sources, such as light emitting diodes, can produce illumination with a variety of characteristics. Different applications may require different levels of performance in terms of coherence, intensity, uniformity of the light projected, as well as the illumination pattern produced.
At the same time, many lighting applications call for the ability to change the size of a projected light spot. For example, flashlights, spotlights, and adjustable or customizable lighting systems, among others, can all make use of such variable-focus capabilities. However, creating such an adjustable light is challenging. To date, lighting systems with variable-focus features have typically utilized a reflector that simply can be moved with respect to a light source to change the size of a light spot projected onto a target surface. The capabilities of these lighting systems—and consequently the products in which they are used—are limited and their illumination characteristics sub-optimal.
Accordingly, there is a need for improved lenses and lighting systems, and particularly those that can produce an adjustable light pattern.